On Mon, Aug 18, 2025 at 05:11:07PM +0200, Miklos Szeredi wrote:
> On Fri, 18 Jul 2025 at 01:27, Darrick J. Wong <djwong@xxxxxxxxxx> wrote:
> >
> > From: Darrick J. Wong <djwong@xxxxxxxxxx>
> >
> > Actually copy the attributes/attributes_mask from userspace.
> >
> > Signed-off-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
> > ---
> > fs/fuse/dir.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> >
> > diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
> > index 45b4c3cc1396af..4d841869ba3d0a 100644
> > --- a/fs/fuse/dir.c
> > +++ b/fs/fuse/dir.c
> > @@ -1285,6 +1285,8 @@ static int fuse_do_statx(struct mnt_idmap *idmap, struct inode *inode,
> > stat->result_mask = sx->mask & (STATX_BASIC_STATS | STATX_BTIME);
> > stat->btime.tv_sec = sx->btime.tv_sec;
> > stat->btime.tv_nsec = min_t(u32, sx->btime.tv_nsec, NSEC_PER_SEC - 1);
> > + stat->attributes = sx->attributes;
> > + stat->attributes_mask = sx->attributes_mask;
>
> fuse_update_get_attr() has a cached and an uncached branch and these
> fields are only getting set in the uncached case.
Hrmm, do you want to cache all the various statx attributes in struct
fuse_inode? Or would you rather that the kernel always call the fuse
server if any of the statx flags outside of (BASIC_STATS|BTIME) are set?
Right now the full version of kstat_from_fuse_statx contains:
if (sx->mask & STATX_BTIME) {
stat->btime.tv_sec = sx->btime.tv_sec;
stat->btime.tv_nsec = min_t(u32, sx->btime.tv_nsec, NSEC_PER_SEC - 1);
}
if (sx->mask & STATX_DIOALIGN) {
stat->dio_mem_align = sx->dio_mem_align;
stat->dio_offset_align = sx->dio_offset_align;
}
if (sx->mask & STATX_SUBVOL)
stat->subvol = sx->subvol;
if (sx->mask & STATX_WRITE_ATOMIC) {
stat->atomic_write_unit_min = sx->atomic_write_unit_min;
stat->atomic_write_unit_max = sx->atomic_write_unit_max;
stat->atomic_write_unit_max_opt = sx->atomic_write_unit_max_opt;
stat->atomic_write_segments_max = sx->atomic_write_segments_max;
}
if (sx->mask & STATX_DIO_READ_ALIGN)
stat->dio_read_offset_align = sx->dio_read_offset_align;
In theory only specialty programs are going to be interested in directio
or atomic writes, and only userspace nfs servers and backup programs are
going to care about subvolumes, so I don't know if it's really worth the
trouble to cache all that.
The dio/atomic fields are 7x u32, and the subvol id is u64. That's 40
bytes per inode, which is kind of a lot.
--D
> Thanks,
> Miklos
>
